E2000 mazda tray top .weak fluid pressure from master ,fcylinder to caliper foot pedal does not pump up pressure enough to bleed caliper

When you are bleeding brakes, the pressure from the pressed brake pedal is pushing the fluid out the bleeder screw. The caliper piston will not move until you close the bleeder valve and press the brake pedal.

It is possible you got a bad master cylinder--even new parts can be bad. Are you following correct bleeding procedure? Starting with right rear, then left rear, right front then left front? Using a helper to pump the pedal slowly then hold to the floor as you open bleed screw, watch for bubbles then close it before pedal is released? Top up fluid often and insure it never gets low enough to suck in air? I once got a "new" master that had no check valve installed.

Hi would seem like the internal seals in the master cylinder are letting fluid past, If after you have pumped it a couple of times if you just rest your foot on the peddle with slight pressure will it slowly go to the floor this is a sure sign, You need to replace or recondition the master cylinder

to bleed brakes is a relatively easy job for two people although it can be done by one without a pressure bleeder.NOTE keep brake fluid levels above minimum at all times during bleeding ( forgot to do it my self on more than one occasion and had to start over, trying to do too much at once) To do by your self you will need the correct ring spanner for bleed nipple, a clear tube that is a tight fit on bleed nipple ( long enough to reach down to floor) and a container with about an inch of brake fluid in it (glass jar will do it, is easier to see fluid level), Starting with the cylinder/caliper at rear furtherts from master cyl (longest brake line from tee piece) place spanner on bleeder then fit tube, placing other end of tube into container below level of fluid,. release master cyl cap/lid (no need to remove completely) undo bleeder half a turn, watch for fluid in clear tube. this should start to flow within 10 to 15 seconds (if bleeder isn't blocked with road grime clean if required), if fluid doesn't flow by it self (it should but) tighten bleeder then release again quarter of a turn, apply foot pressure to brake pedal, hold pressure on pedal till you feel pedal dropping towards the floor (half inch of pedal travel should be enough) ( fluid in container will stop air being drawn into brake lines when you release brake pedal) check clear tube for fluid/bubbles, open bleeder further quarter turn, if fluid has filled clear tube allow fluid to fill container a further eight of an inch, then close off bleeder (make sure no bubbles appear in tube whilst this is happening other wise drain more fluid till only brake fluid is visible in tube ) repeat process on opposite wheel cyl/caliper, then repeat process on front caliper furthest from master cyl , then the caliper closest to master cyl last. If two people are doing the bleeding the same clear tube and container are used,as is the order in which cyl/calipers are bled. One sits in the car and pumps the pedal until it has some resistance under foot (Whilst the pedal is held down) second person releases bleeder, first person keeps pressure on pedal whilst bleeder is released (pedal will travel towards the floor) when pedal has been depressed as far as it will travel second person closes bleeder before, the first person releases pedal and pumps the pedal again repeating the process until no air bubbles appear in clear tube at this cyl/caliper before moving to next cyl/caliper. good communication must be maintained to make this process hassle free

First bench bleed the master cylinder. Or if its still on the car do this, have some one pump the pedal hold and open one line,do this three times, move to the next line pump three time hold and open the line. Hows the pedal. getting firmer no go ahead bleed as usual. let me know we can fix this together

Well, if you change a caliper or a brake line the fluid in the master cylinder should remain, even if the fluid leaks out.

However, if you are having trouble bleeding regularly, then use a vacuum pump with a 'can' or use a pressure bleeder (I prefer this method) that costs about $55 or so available on the Internet.

If you use a pressure bleeder, you'll need an extra master cylinder cap that has a hole drilled in it to accomodate the fittings of the pressure bleeder.

I know someone who had a Lincoln Continental that changed a brake line and had trouble bleeding it, and they used a vacuum pump and it bled easily using that method.

Some cars require that when you change the master cylinder, a brake scan tool is required to bleed the master cylinder that has air in it. But, if you did not replace the master cylinder, you should be able to use either the vacuum or pressure method to bleed the brakes easily.

Good luck on this repair.

did u bleed the brakes ? there could be an air bubble causing blockage

Hi,
Have someone pump the brake pedal and hold foot pressure it. Loosen the bleeder screw and air or fluid should shoot out... it's under pressure. Tell the person to not lift up on the pedal until you tighten the bleeder, or they'll draw air back into the line. They'll feel the pedal go down to the floor. Keep applying pedal pressure till the bleeder is tightened. Repeat the process till all air is out. They will have a "good pedal" shortly.
Do each wheel, and remember to refill the master cylinder as you lose fluid.
Hope this helps... Good luck!

It's very possible to be the master cylinder, the o-rings on the piston could be worn, letting the fluid seep back through instead of getting full pressure through the lines. Could also be the brake booster.
Try changing the master cylinder first, which is cheaper and easier, and see if there is a difference, you'll need to bleed the brakes again.
To check the booster,
With the engine off, pump the brakes until the pedal is hard, then hold pressure on the brake pedal and listen for air escaping, or the pedal goes slowly to the floor, Do that after the master cylinder has been changed, at least that will be eliminated.

Try using a pressure bleeder. It will force the air out. Works every time.